The invention concerns an arrangement for displacing a displacement member along a stationary base.
A typical use of such an arrangement for displacing a displacement member along a stationary base is for example in relation to vehicle seats for adjusting the seat squab of the vehicle seat to a desired position in relation to a support base structure.
A form of arrangement for displacing a displacement member, for example in the case of a vehicle seat for displacement of the squab in relation to a support base structure, includes an elongate actuating member which engages with the displacement member to produce a sliding movement thereof. In such an arrangement the elongate actuating member may be formed by a screw spindle and the displacement member may be formed by a nut member, the screw spindle and the nut member being dimensioned to afford a self-locking effect so that after displacement of the arrangement, by rotation of the screw spindle in a respective direction of rotation, the arrangement is automatically prevented from moving out of its set position when that is not wanted, by virtue of the screw spindle rotating in the opposite direction. The screw spindle is screwed through the nut member and that requires a suitable degree of precision in terms of the cooperation thereof. In addition, displacement of the displacement member in relation to the stationary base can be relatively time-consuming, depending on the respective screwthread pitch of the screw spindle and the nut member.
An object of the present invention is to provide an arrangement for displacing a displacement member along a stationary base, which is of a simple structure while affording reliability of operation and which is of a small structural height for enhanced ease of installation.
Another object of the present invention is to provide an arrangement for displacing a displacement member along a stationary base which is simple to actuate and which makes it possible to achieve long displacement travel movements without involving a great deal of time to produce same.
Still another object of the present invention is to provide an arrangement for displacing a displacement member along a stationary base, by means of a simple actuating movement and also affording a self-locking action.
In accordance with the principles of the present invention the foregoing and other objects are attained by an arrangement for displacing a displacement member along a stationary base, by means of an elongate actuating member. The displacement member has at least one linear tooth means, wherein first and second axially mutually spaced ratchet members are pivotably mounted on the actuating member at at least one longitudinal edge thereof, the ratchet members including with each other an opening angle and being provided with ratchet tooth means adapted to the linear tooth means on the displacement member. The ratchet members are urged towards the linear tooth means by means of spring members. Between the at least one linear tooth means on the displacement member and the actuating member is a disengagement member for the respective ratchet member, the disengagement member being fixed with respect to the base and determining the respective linear displacement advance movement step in one direction of displacement or the other opposite direction of displacement. Frictional conditions between the displacement member and the stationary base are such that the actuating member entrains the displacement member in a stepwise movement in a ratcheting mode in the respective one direction of displacement or the other opposite direction, but in the direction opposite to the respective direction of displacement the displacement member is secured to the base by frictional engagement and only the actuating member is moved back in ratcheting mode in relation to the displacement member by the displacement advance movement step.
In a preferred feature of the invention the elongate actuating member is in the form of an elongate plate or bar member. It may involve a stamped sheet metal member.
In a further preferred feature of the invention, affording a displacement arrangement of a very simple structure without requiring the use of mounting pins or journals, the elongate actuating member, at at least one longitudinal edge thereof, is provided with first and second round recesses disposed at a spacing from each other in the elongate direction of the actuating member, wherein a respective ratchet member has a round mounting portion which is pivotably movably mounted in a respective one of the recesses in the actuating member. Such an arrangement not only has the advantage that mounting journals are not required for supporting the ratchet members, but the assembly complication is very low because the ratchet members, with their round mounting portions, are pivotably mounted in a virtually floating condition in the recesses in the elongate actuating member.
A preferred configuration of the displacement arrangement according to the invention provides that first and second spring members are mounted at at least one longitudinal edge of the actuating member, for urging the operatively associated ratchet members towards the position of engagement with the linear tooth means on the displacement member.
In a further preferred feature of the invention the at least one linear tooth means, the elongate actuating member and the at least one pair of ratchet members are of thickness dimensions which at least approximately correspond to each other. Such a design configuration results in the arrangement according to the invention being of a very small overall thickness so that the amount of space required for the arrangement for example in relation to a vehicle seat is advantageously small.
A further preferred feature of the invention provides that the spring members are in the form of leaf springs which are of a thickness dimension adapted to the ratchet members and the actuating member.
In a preferred feature the ratchet members are secured to the actuating member by means of a cover plate member fixed to the actuating member, the cover plate member being of small wall thickness, with the spring members projecting from the cover plate member as integral components thereof. Such a cover plate member with integrally projecting spring members can be easily produced from a portion of spring plate of small wall thickness by suitable stamping and bending operations. The assembly complication and expenditure for combining the spring members with the ratchet members is also advantageously low in this case.
In a further preferred feature of the invention the at least one disengagement member for the ratchet members is provided on a central lengthwise portion of the base, thereby affording a double-acting linear ratchet displacement arrangement, in other words, a displacement arrangement in which the displacement member is linearly displaceable in a stepwise ratcheting mode by means of the actuating member in one direction or in the other opposite direction.
From the points of view of uniform loading or stressing of the arrangement and wear of the arrangement according to the invention, it is preferable if the displacement member has first and second linear tooth means which are disposed at a spacing from each other and which are oriented in parallel relationship and between which the elongate actuating member is disposed at equal spacings from the first and second linear guide means. A respective pair of ratchet members is pivotably mounted to the actuating member at each of the two longitudinal edges thereof, the ratchet tooth means of the ratchet members being urged towards the correspondingly associated linear tooth means by means of respectively associated spring members. A respective disengagement member which is fixed with respect to the base is operatively disposed between each linear tooth means and the associated longitudinal edge of the actuating member.
Further objects, features and advantages of the invention will be apparent from the description hereinafter of a preferred embodiment.